Storage network management server, storage network managing method, storage network managing program, and storage network management system

ABSTRACT

In a system which manages path information and status of network with respect to a path being used for access to a storage apparatus and has a redundant path, when a fault occurs in the network, whether or not the path can be recovered by rerouting in network apparatuses is discriminated, thereby performing proper path switching. Construction information and the path information of the network are managed as information of the path which is being used for a storage access by a management server. Further, when the access path is made redundant, the management server obtains fault information in the network and information showing whether or not the path is being reconstructed from the network apparatuses, thereby discriminating the necessity of the path switching. If the path switching is necessary, the management server notifies a host computer and the storage apparatus of it and each apparatus executes a switching process.

INCORPORATION BY REFERENCE

The present application claims priority from Japanese applicationJP2004-262811 filed on Sep. 9, 2004, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

The invention relates to a storage network management server, a storagenetwork managing method, a program for managing a storage network, and astorage network management system.

In conventional storage management, connecting relations between a hostcomputer and storage apparatuses are grasped and paths as connectingpaths to the storage apparatuses are managed on the basis ofconstruction information of network apparatuses (for example, a switchand a router).

As a method whereby in a storage network, paths between the hostcomputer and the storage apparatuses are managed on the basis of a portconnecting relation among switches and a traffic situation of each pathis managed, there is a method shown in U.S. 2004/0024870.

A method whereby not only the paths between the host computer and thestorage apparatuses are managed but the paths between the storageapparatuses are also automatically selected in accordance with a policyof the user when data in one storage apparatus is remote-copied toanother storage apparatus is shown in U.S. 2002/0143999.

In recent years, use of an IP (Internet Protocol) network as a storagenetwork has advanced the network to be enlarged in scale and come a longdistance. A managing technique of the IP network enables the managementof information of the paths between the apparatuses such as routinginformation, the number of hops, and the like. To improve faultresistance, the network apparatuses are provided with a path controlfunction of automatically switching from a path with a fault to anotherpath, if any, which can avoid the fault.

In the management of the access paths to the storage apparatuses, in thecase of an SAN (storage area network) of a small scale by directconnection or a fiber channel switch, the paths can be easily graspedfrom the connecting relation of the ports.

However, in an IP storage area network (hereinbelow, abbreviated toIP-SAN) using the IP network which can be realized in the large scaleand the long distance, the network is complicated and there is such aproblem that a load is heavy in the case of managing the pathinformation of the network and the paths for the storage accessesaltogether.

In the case where the path is automatically recovered by the pathcontrol function of the IP network when a fault occurs on the pathbetween the host computer and the storage apparatus, there is a casewhere the access is recovered without switching the paths. However,hitherto, there is no means for recognizing such network information.

SUMMARY OF THE INVENTION

It is an object of the invention to realize proper path switching when afault occurs in a network in a system which manages paths which are usedto access storage apparatuses together with path information of thenetwork and which has a redundant path (path for standby).

To accomplish the above object, according to the invention, there isprovided a storage network management server for instructing to switchpaths when a fault occurs in a network which connects one or moreinformation processing apparatuses and one or more storage apparatuses,comprising: a storing apparatus for storing, every session, a sessionmanagement table showing identification information of the informationprocessing apparatus and the storage apparatus serving as initiators andthe storage apparatus serving as a target in this session,identification information of the path which is being used at present inthe session, and identification information of a standby path; an eventnotification receiving unit for receiving event notifications regardingthe faults of each of the apparatuses and network apparatuses connectedto each of the apparatuses from the one or more information processingapparatuses and the one or more storage apparatuses; an active pathdiscriminating unit for making discrimination to switch from an activepath to the standby path with reference to the session management tablein the case where it is determined on the basis of a transmitting sourceof the received event notification and contents of this eventnotification that the fault has occurred in one of the networkapparatuses in the path which is being used at present by each of theapparatuses; and a path setting instructing unit for transmitting theinstruction to switch from the active path to the standby path to eachapparatus on the basis of a discrimination result of the active pathdiscriminating unit. Other constructions will be explained in thefollowing embodiment.

According to the invention, in the system which manages the paths to beused for an access to the storage apparatuses together with the pathinformation of the network and has the redundant path (path forstandby), the proper path switching can be realized when the faultoccurs in the network.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a constructional diagram of a storage network system in anembodiment of the invention;

FIG. 2 is a constructional diagram of a storage apparatus in FIG. 1;

FIG. 3 is a constructional diagram of a host computer in FIG. 1;

FIG. 4 is a hardware constructional diagram of a management server inFIG. 1;

FIG. 5 is a module constructional diagram of a function of themanagement server in FIG. 1 (module constructional diagram of a pathmanaging program);

FIG. 6 is a diagram showing an example of a construction of an apparatusmanagement table held in the management server in FIG. 1;

FIG. 7 is a diagram showing an example of a session management tableheld in the management server in FIG. 1;

FIG. 8 is a diagram showing an example of a path management table heldin the management server in FIG. 1;

FIG. 9 is a flowchart showing a processing procedure upon path settingof the management server in FIG. 1;

FIG. 10 is a flowchart showing a processing procedure of the managementserver in FIG. 1 when a fault occurs;

FIG. 11 is a diagram for explaining a mechanism of reconstruction of apath by a network apparatus in FIG. 1; and

FIG. 12 is a diagram showing an example of the path switching when thefault occurs.

DESCRIPTION OF THE EMBODIMENT

A best mode for carrying out the invention (hereinafter, referred to asan embodiment) will be described hereinbelow with reference to thedrawings.

FIG. 1 is a system constructional diagram of the embodiment of theinvention.

The system of the embodiment is constructed by including: a hostcomputer (information processing apparatus) 102; storage apparatuses 103(103A, 103B); a network 105 for connecting the host computer 102 and thestorage apparatuses 103 (103A, 103B); a storage network managementserver (management server) 101; and a network 106 for management.

The network 105 is, for example, an IP network and constructed bynetwork apparatuses 104 such as router, switch, and the like.

Although the host computer 102 and the storage apparatuses 103 (103A,103B) are directly connected to the network 105 in FIG. 1, they can bealso connected through a local area network (LAN). Although only onehost computer 102 and two storage apparatuses 103 (103A, 103B) areillustrated in FIG. 1 for simplicity of explanation, the number of hostcomputers and the number of storage apparatuses are not limited to suchnumbers.

Data accompanied with data accesses such as writing and reading of datainto/from a disk is transferred among the host computer 102 and thestorage apparatuses 103. Data is transferred among the storageapparatuses 103 by using functions such as data copy accompanied withdata backup, virtual realization and external connection of the storageapparatuses 103.

Although an IP (Internet Protocol) is used as a communication protocolof the network 105 in the embodiment, the communication protocol is notlimited to it. A protocol such as iSCSI (Internet Small Computer SystemInterface) or the like is used for a storage access on the IP. Further,the management server 101 to manage a path of the storage access isconnected to each of the host computer 102 and the storage apparatuses103 through the network 106 for management.

In the embodiment, the host computer 102 and the storage apparatuses 103are collectively properly abbreviated as “apparatuses” and the networkapparatuses 104 are also properly abbreviated as “apparatuses”.

FIG. 2 is a constructional diagram of the storage apparatus in FIG. 1.The storage apparatus 103 is constructed by including: a CPU 201; amemory 202; a storing apparatus group 204 comprising one or more logicunits 205; a storing apparatus 203 for storing control information andthe like of the logic units 205; and one or more network interfaces(network I/F) 206.

The network I/F 206 is a communication interface for allowing thestorage apparatus 103 to communicate with the host computer 102, otherstorage apparatuses 103, the management server 101, or the like throughthe network 105 or the network 106 for management.

The CPU 201 loads a storage control program for controlling the logicunits 205 and a communication control program 207 for making control ofthe communication with other apparatuses such as switching or the likeof a using port into the memory 202 and executes. It is assumed thatthose programs have been stored in the storing apparatus 203.

FIG. 3 is a constructional diagram of the host computer in FIG. 1. Thehost computer 102 is constructed by including: a CPU 301; a memory 302;a storing apparatus 303; one or more network interfaces (network I/F)304; and an input/output interface (input/output I/F) 305.

The CPU 301 loads an application program (hereinafter, abbreviated toAP) 307 and a communication control program 306 into the memory 302 andexecutes. The CPU 301 determines the network I/F 304 to be used by thecommunication control program 306 in accordance with set informationtransmitted from the management server 101.

The CPU 301 accesses the storage apparatus 103 (refer to FIG. 2) throughthe communication control program 306 by the AP 307 and inputs/outputsthe data into/from the storing apparatus group 204.

The storage apparatus 103 serving as an access destination is called atarget and the apparatus serving as an accessing source is called aninitiator. Although an explanation will be made on the assumption thatthe host computer 102 is set to the initiator in the embodiment, thestorage apparatus 103 can be also set to the initiator.

A connection relation between the initiator and the target is called asession. The session is identified by an initiator node name(identification information of the apparatus serving as an initiator), atarget node name (identification information of the apparatus serving asa target), and the number of the logic unit 205. Further, a connectingpath (path) is identified by each apparatus and a network address ofeach apparatus.

FIG. 4 is a hardware constructional diagram of the management server inFIG. 1. The management server 101 is constructed by including a CPU 401;a memory 402; a storing apparatus 403; a network interface (network I/F)404; and an input/output interface (input/output I/F) 405. Although thestoring apparatus 403 and the memory 402 are the independent apparatusesin the embodiment, the memory 402 can be also substituted for thestoring apparatus 403.

A path managing program (program for managing the storage network) 406is stored in the storing apparatus 403, loaded into the memory 402, andexecuted by the CPU 401. An apparatus management table, a sessionmanagement table, and a path management table are stored in the storingapparatus 403. Details of those tables will be explained hereinafter.

Although the management server 101 is shown as independent hardware inFIG. 1, the path managing program 406 can be also executed together withother programs in an information processing apparatus having hardwareconstructing elements similar to those in FIG. 4, the storage apparatus103, or the network apparatus 104. That is, the function (path managingprogram) of the management server 101 can be also installed as a part ofthe storage apparatus 103 or the network apparatus 104 (refer to FIG.1).

FIG. 5 is a module constructional diagram of the function of themanagement server in FIG. 1 (module constructional diagram of a pathmanaging program).

The management server 101 is constructed by including: a storage accessinformation collecting unit 501 for obtaining access information (a nodename and an interface number of the host computer 102, a node name, aninterface number, a logic unit number, and the like of the storageapparatus 103) from the host computer 102 (refer to FIG. 1) or thestorage apparatus 103 to another storage apparatus 103; a networkinformation collecting unit 502 for obtaining construction information(an interface number of the network apparatus 104, an address set inthis interface, and the like) and path information from the networkapparatus 104; an event notification receiving unit 503 for receiving anevent notification from each apparatus; a path information managing unit504 for properly updating the apparatus management table, sessionmanagement table, and path management table in the storing apparatus403; an active path discriminating unit 506 for discriminating(determining) the path which is being used in each apparatus when theevent notification is received or the like; and a path settinginstructing unit 507 for notifying the host computer 102 or the storageapparatus 103 of the path determined in the active path discriminatingunit 506. Details of the operations of those constructing elements willbe described hereinafter.

Those constructing elements are realized by a method whereby the CPU 401of the management server 101 loads the path managing program into thememory 402 and executes it.

FIG. 6 is a diagram showing an example of a construction of theapparatus management table held in the management server in FIG. 1. Inthe apparatus management table, with respect to each apparatus whichbelongs to the network 105 that is managed by the management server 101,the interface information of each apparatus is shown every apparatus ID(identification information) for identifying the apparatus. When thenetwork is constructed or an apparatus is added or deleted, the contentsof the apparatus management table are updated by the manual input by theadministrator through the input/output I/F 405 or the obtainment of theinformation from each apparatus via the network 105 (or the network 106for management).

As shown in FIG. 6, the apparatus management table is constructed byincluding, for example: an apparatus ID field 601 for identifying theapparatus; a managing address field 602 for managing the address that isused for communication of management information; an interface numberfield 603 for managing each interface information; an address field 604;and a performance field 605 showing a processing speed of the interface.

In FIG. 6, the managing address of the apparatus of the apparatus ID“R1” is equal to “192.168.2.2”. The address of the interface of theinterface number “1” is equal to “192.168.2.2”. The performance(bandwidth) of this interface is equal to “2 G (bps)”.

The session management table will now be described with reference toFIG. 7.

FIG. 7 is a diagram showing an example of the session management tableheld in the management server in FIG. 1.

As shown in FIG. 7, the session management table shows the connectioninformation to the target (the storage apparatus 103) and the availablepath information and is constructed by including: a session ID field 701for storing a session identifier (identification information); anapparatus ID field 702 of the initiator for managing the apparatus ID ofthe initiator; a node name field 703 of the initiator; a targetapparatus ID field 704 for managing the apparatus ID of the target; anode name field 705 of the target; a logic unit (LU) number field 706 ofthe target; an active path ID field 707 for managing the identifier ofthe path (path ID); and a standby path ID field 708.

For example, in the session management table in FIG. 7, the session ofthe session ID “1” shows that the initiator is the apparatus ID “S1” andthe node name “ign.2004.com.a:srv1”, and targets are the apparatus ID“T1 and the node name “ign.2004.com.a:str1” the LU number “1”, and thepath of the path ID “1” is in the active mode, and the path of the pathID “2” is in the standby mode.

It is now assumed that the initiator (the host computer 102) allocatesthe session identifier (session ID) on the basis of the communicationcontrol program 306 (refer to FIG. 3) at the time of the connectionafter the end of the path setting and the management server 101 obtainsthis identifier and stores it. The management server 101 unconditionallyallocates the path identifier (path ID).

Although it is assumed that the path is duplexed in the embodiment, inthe case where the path is a simplex, an active path is set into theactive path ID field 707 in the session management table and a standbypath is not set into the standby path ID field 708. In this case, thepath switching process by the management server 101 is not executed. Thepath can be constructed as a triplex or more and in such a case, aplurality of path information is set into the field of the active pathor the standby path.

The management server 101 obtains the connection information of the hostcomputer 102 and the storage apparatus 103 when the network isconstructed, the construction of the new host computer 102 or storageapparatus 103 is changed, or the like and registers it into the sessionmanagement table (refer to FIG. 7). The connection information at thistime is obtained by either a method whereby the administrator inputs itby using the input/output I/F 405 of the management server 101 when hesets the permission of the access to the storage apparatus 103 or amethod whereby each apparatus transmits the set information of theapparatus to the management server 101. In the case of obtaining theconnection information from each apparatus, it is also possible that themanagement server 101 requests each apparatus to transmit it everypredetermined period or the management server 101 is notified uponsetting of each apparatus.

The path management table will now be described with reference to FIG.8.

FIG. 8 is a diagram showing an example of the path management table heldin the management server in FIG. 1.

As shown in FIG. 8, the path management table shows the addressinformation of the network apparatuses 104 through which data is passedin the path every path. The path management table is constructed byincluding: a path ID field 801 for setting a path identifier (pathidentification information); an initiator address field 802 forregistering an address of the initiator; a target address field 803 forregistering an address of the target; a via-apparatus address field 804for registering addresses of the interfaces of the network apparatuses104 through which the data is passed in the path in the connectionbetween the initiator and the target; a hop number field 805 forregistering the number of hops as performance information of the path; abandwidth field 806 for registering a band; and a path field 807 forsetting a status of the path.

For example, in the path management table in FIG. 8, in the path of thepath ID “1”, the address of the initiator is equal to “192.168.2.10”,the address of the target is equal to “192.168.4.10”, the addresses ofthe interfaces of the apparatuses which pass the data via the path inthe connection between the initiator and the target are equal to“192.168.2.2”, “192.168.3.3”, “192.168.3.2”, and “192.168.4.1”, thenumber of hops is equal to “2”, the band is equal to “1 G (bps)”, andthe status of the path is “UP (under operation)”, respectively.

It is assumed that with respect to the addresses which are used by thetarget and the initiator in the path (the address in the target addressfield 803 and the address in the initiator address field 802 in FIG. 8),the storage access information collecting unit 501 obtains theinformation of each apparatus simultaneously with the creation of thesession management table and the path information managing unit 504registers those addresses on the basis of the obtained information.

It is also assumed that the network information collecting unit 502obtains the address in the via-apparatus address field 804 from thenetwork apparatus 104 and the path information managing unit 504registers it.

The storage access information collecting unit 501 and the networkinformation collecting unit 502 of the management server 101 obtainthose information from the storage apparatus 103, the host computer 102,and the network apparatus 104 at every predetermined period.

In the case where the bandwidth (information in the bandwidth field 806)differs every hop, the minimum value when seen from the whole path isregistered.

With respect to the path status (information in the path field 807), thenetwork information collecting unit 502 obtains the informationregarding the statuses (operation statuses) of the network interfaces ofthe network apparatuses 104 from the network apparatuses 104 throughwhich the data is passed in the path. That is, the storage accessinformation collecting unit 501 periodically obtains connectionsituations to the network 105 from the initiator and the targets of therelevant path. The path information managing unit 504 discriminates oneof the modes of “under operation (UP)”, “under stop (DOWN)”, and “underroute creation (ROUTE)” with respect to each path on the basis of thoseinformation and registers the determined mode.

It is assumed that a managing protocol (for example, SNMP: SimpleNetwork Management Protocol) is used for communication between themanagement server 101 and each apparatus and device. Each of theforegoing information can be transmitted to the management server 101 byexecuting a managing agent program in each apparatus or device or can bealso transmitted by executing a predetermined communication controlprogram.

A path setting process in the case where an apparatus was newly added,where a path is added, or the like will now be described with referenceto FIG. 9 (FIGS. 1 to 8 are also properly referred to).

FIG. 9 is a flowchart showing a processing procedure upon path settingof the management server in FIG. 1.

The management server 101 obtains the access information which is usedto access the storage apparatus 103 from the host computer 102 (or thestorage apparatus 103) (step S901).

The storage access information collecting unit 501 can obtain the accessinformation through the network 106 for management or the network 105,or the administrator can also input it through the input/output I/F 405of the management server 101.

The access information which is obtained by the storage accessinformation collecting unit 501 is information regarding the node nameand the interface number of the initiator and the node name, theinterface number, and the logic unit number of the target.

If there is a possibility that the host computer 102 and the storageapparatus 103 use a plurality of interfaces, the storage accessinformation collecting unit 501 also obtains the interface numbers ofall initiators of each apparatus while including information showingwhether the interface is used or in the standby mode.

In the management server 101, the path information managing unit 504(FIG. 5) allocates the path identifier (path ID) every path, obtains theaddresses of the network interfaces of the initiator and the target withreference to the interface number obtained in step S901 and theapparatus management table (FIG. 6), and registers it into the pathmanagement table (FIG. 8).

Subsequently, the network information collecting unit 502 obtains thepath information from the network apparatuses 104 through which the datais passed between the interface of the initiator and the interface ofthe target (S902). The path information which is obtained here is theaddresses of the network apparatuses 104 through which the data ispassed in the path and the like. When the path information is obtainedin step S902, the construction information of the network apparatus 104(the interface number of the network apparatus 104 and the address,bandwidth, and the like set in this interface) is also obtained.

The path information managing unit 504 registers the obtainedinformation into the session management table (FIG. 7) and the pathmanagement table (FIG. 8), respectively. If a plurality of interfaceinformation is obtained from the apparatuses, it is determined thatanother path (standby path) exists (YES in S903) and the processingroutine is returned to step S902. The path information using such aninterface (and the construction information of each network apparatus104) is obtained again.

After completion of the obtainment of the path information regardingeach path, in other words, if it is determined that there is no anotherpath (NO in S903), the active path discriminating unit 506 selects thepath to be used on the basis of the obtained path information and theconstruction information of each network apparatus 104 (S904). If thereis one path, this path is selected. If there are two or more paths, theperformance of the paths such as band and the number of hops arecompared and the proper one is selected. As a selecting rule in thiscase, for example, there is such a rule that the band is regarded as apriority discrimination material, the path of the largest band is used,and other paths are set to standby paths.

The path setting instructing unit 507 sets the path selected in stepS904 into the initiator and the target through the network 106 formanagement or the network 105 (S905) and finishes the process once. Uponsetting of the path in each apparatus such as initiator (the hostcomputer 102), the target (the storage apparatus 103), or the like, aninstruction message is transmitted by the managing agent program (agentprogram by the SNMP or the like mentioned above) of each apparatus,thereby allowing each apparatus to make the setting, or the managementserver 101 can also directly instruct each apparatus to execute a pathsetting command.

The node name of the initiator, the address of the interface to be usedin the initiator, the node name of the target, the LU number, and theaddress of the interface to be used in the target are included in theinstruction message which is transmitted at this time.

The path information managing unit 504 registers the set path into theactive path ID field 707 (FIG. 8) in the session management table.

The initiator is connected to the target by using the interfacedesignated from the management server 101. Upon connection, theinitiator transmits the session identifier (session identificationinformation) that is unconditionally allocated to the management server101.

Further, a time-out value to wait for a response from the target is setin the initiator. Each apparatus obtains the band and the number of hopsof the active path from the management server 101 by the managing agentprogram, or it is also possible to include the information such as bandand the number of hops of the path into the instruction message from themanagement server 101 side and transmit it.

The managing agent program calculates the time-out value by substitutingthe band and the number of hops into a predetermined calculatingequation.

The initiator sets the time-out value at this time into a responsewaiting time which is used in the communication control program of theinitiator. If the time-out value exceeds the response waiting time, theinitiator determines that the communication control program cannot becommunicated. If it cannot be communicated, an event notificationshowing such a fact is transmitted to the management server 101.

In the target (the storage apparatus 103) which received the instructionmessage, a mode to use the interface designated from the managementserver 101 is set on the basis of the communication control program.Further, in the case where using interface information of the initiatoror its own storage apparatus 103 is designated to the access limitationto the logic unit 205, the path is set on the basis of the instructionmessage. In this manner, each apparatus and each device sets the path.

The processes of the management server 101 when a fault occurs will nowbe described with reference to FIG. 10 (FIGS. 1 to 9 are also properlyreferred to).

FIG. 10 is a flowchart showing a processing procedure of the managementserver in FIG. 1 when a fault occurs.

In each apparatus such as host computer 102, storage apparatuses 103, orthe like, its own status and the status of the apparatus on theconnection destination side are monitored. If it is determined that thestatus of each apparatus is abnormal (the fault occurred), an eventnotification showing such a fact is transmitted to the management server101 (FIG. 1). The management server 101 receives the event notificationby the event notification receiving unit 503 (FIG. 5) (S1001).

Subsequently, the active path discriminating unit 506 discriminateswhether the fault has occurred in the target (the storage apparatus 103)or the network apparatus 104 on the basis of the transmitting source andthe contents of the event in the event notification.

For example, in the case where the event notification receiving unit 503of the management server 101 receives from the initiator (the hostcomputer 102) such an event showing that the initiator cannot access thetarget (the storage apparatus 103), that is, the response waiting fromthe target has timed out in the initiator, the active pathdiscriminating unit 506 of the management server 101 confirms the statusof the target (the storage apparatus 103) (S1002). On the basis of aresponse from the storage apparatus 103, the active path discriminatingunit 506 discriminates whether or not the fault has occurred in thestorage apparatus 103 (S1003).

At this time, the active path discriminating unit 506 discriminates onthe basis of information showing the presence or absence of the eventnotification from the storage apparatus 103 or the presence or absenceof the event notification from another initiator showing that theinitiator cannot access the storage apparatus 103.

If the storage apparatus 103 did not normally respond to the statusconfirmation from the management server 101, it is determined that thefault occurred in the storage apparatus 103 (YES in step S1003) and theadministrator is notified that the fault occurred in the storageapparatus (step S1007). For example, a message showing that the faultoccurred in the storage apparatus 103 is outputted to a display unit orthe like (not shown) of the management server 101 and the processingroutine is finished once.

If the active path discriminating unit 506 determined that the storageapparatus 103 normally responded and no fault occurs (NO in S1003), theinformation of each network apparatus 104 is collected and the status ofthe network 105 (each network apparatus 104) is confirmed on the basisof the information of the network apparatuses 104 (S1004).

That is, the active path discriminating unit 506 specifies the networkapparatuses 104 through which the data is passed in the relevant pathwith reference to the path management table and the apparatus managementtable. The active path discriminating unit 506 confirms the status ofthe specified network apparatus 104.

In the status confirmation at this time, whether or not each networkapparatus 104 can reconstruct (reroute) the path is confirmed and, if itcan reconstruct the path, whether or not the rerouting process is atpresent being executed is also confirmed.

On the basis of a response result of the status confirmation, the activepath discriminating unit 506 discriminates whether or not each networkapparatus 104 is in the normal state, or whether or not the eventnotification has been sent from each network apparatus 104 is confirmed.That is, whether or not the fault has occurred in one of the networkapparatuses 104 on the path that is being used at present isdiscriminated (S1005).

If the active path discriminating unit 506 determined that no faultoccurs in the network apparatuses 104 (NO in S1005), the processingroutine is finished as it is.

If the active path discriminating unit 506 determined that the fault hasoccurred in the network apparatus 104 (YES in S1005), whether or not thenetwork apparatus 104 is rerouting at present is discriminated (S1006).

A mechanism of the reroute (reconstruction of the path) by the networkapparatuses 104 will now be described with reference to FIG. 11 (FIGS. 1to 10 are also properly referred to). FIG. 11 is a diagram forexplaining a mechanism of reconstruction of the path by the networkapparatuses in FIG. 1.

In the network apparatus 104, the information is exchanged by thenetwork apparatuses 104 constructing the network 105 and if theinformation can be sent by another path without passing through thenetwork apparatus 104 in which the fault occurred, the pathreconstruction (reroute) is executed.

For example, in FIG. 11, it is assumed that the fault occurred in arouter 104B in a path 1101 of a router (network apparatus) 104A—therouter 104B—a router 104C of the path connecting the network I/F 304 ofthe host computer 102 and the network I/F 206 of the storage apparatus103. In this case, the routers 104A and 104C can select a path 1102 viaa router 104D.

When the routers 104A and 104C start to reroute, they notify themanagement server 101 (refer to FIG. 1) that the rerouting process isexecuted, or if there is a confirmation from the management server 101,the routers 104A and 104C return a response showing the reroutingprocess is being executed.

Subsequently, when the routers 104A and 104C finish the reroute, theynotify the management server 101 of the event indicative of the end ofthe reroute. If there is a confirmation from the management server 101,the routers 104A and 104C make a response of the end of the reroute.

Returning to the explanation of FIG. 10. When the management server 101obtains the response showing that the network apparatus 104 is reroutingin step S1004, the active path discriminating unit 506 determines thatthe network apparatus 104 is rerouting at present (YES in S1006) and theprocessing routine advances to step S1010.

If the management server 101 did not obtain the response showing thatthe network apparatus 104 is rerouting in step S1004 mentioned above,the active path discriminating unit 506 determines that the networkapparatus 104 is not rerouting (NO in S1006) and step S1037 follows.Processes in step S1037 and subsequent steps will be describedhereinafter.

The active path discriminating unit 506 which determined that thenetwork apparatus 104 is rerouting at present outputs a message showingthat the fault occurs at present in the network 105 and a messageshowing that the path is being reconstructed (under rerouting) to thedisplay unit or the like (not shown) of the management server 101 instep S1010. That is, the active path discriminating unit 506 notifiesthe administrator that the fault of the network 105 occurred and thereroute is being executed. The active path discriminating unit 506 waitsfor the event notification indicative of the completion of the rerouteor a response indicative of the completion of the reroute from thenetwork apparatus 104.

When the management server 101 receives the event notification orresponse indicative of the completion of the reroute from the networkapparatus 104 (YES in S1011), the path information managing unit 504updates the information of the relevant path in the path managementtable (S1012). For example, the path information managing unit 504updates the information of the via-apparatus address field 804, the hopnumber field 805, the bandwidth field 806, and the like in the pathmanagement table in FIG. 8.

The message showing the completion of the path reconstruction(completion of the reroute) in the network 105 is outputted to thedisplay unit or the like (not shown) of the management server 101,thereby notifying the administrator of the completion of the reroute(S1013). The processing routine is finished once.

If the event notification or response indicative of the completion ofthe reroute cannot be received (NO in S1011) even after the lapse of apredetermined time after the management server 101 received the eventnotification or response showing that the reroute is being executed fromthe network apparatus 104 in step S1011, step S1037 follows.

In step S1037, the active path discriminating unit 506 discriminateswhether or not the path can be switched with respect to the path inwhich the fault occurs at present with reference to the session IDincluded in the event notification received in step S1001 and thesession management table. The discrimination here about whether or notthe path can be switched is made by a method whereby the active pathdiscriminating unit 506 discriminates whether or not the standby pathhas been registered in the session management table with respect to thesession in which the fault occurs at present.

That is, for example, in the session of the session ID “1” in thesession management table shown as an example in FIG. 7, if the faultoccurred in the path of the path ID “1”, the active path discriminatingunit 506 discriminates whether or not the standby path has beenregistered in the standby path ID field 708 in the session managementtable. It is also possible to construct in such a manner that if theactive path discriminating unit 506 determined that the standby pathexists, whether or not this standby path is in the state where thecommunication is impossible (DOWN) due to the same fault is alsodiscriminated with reference to the status field 807 (refer to FIG. 8)in the path management table.

If the active path discriminating unit 506 determined here that the pathcan be switched (YES in S1037), the path setting instructing unit 507transmits a setting instruction to switch the path that is being used atpresent to the standby path to the host computer 102 and the storageapparatus 103 (S1038). Further, a message showing that the faultoccurred in the path and a message showing that the path switchingoperation is being executed (under automatic recovery) are outputted tothe display unit or the like (not shown) of the management server 101.That is, the administrator is notified of the occurrence of the fault inthe path and the execution of the path switching operation (S1039). Thepath information managing unit 504 updates the path management table(information of the active path ID field 707 in FIG. 7) in the sessionmanagement table (S1040) and the processing routine is finished.

If the active path discriminating unit 506 determined that the pathcannot be switched (NO in S1037), the administrator is notified that thefault occurred in the path and the path cannot be switched (S1020). Thatis, the message showing that the fault occurred in the path and amessage showing that the path cannot be switched (automatic recovery isimpossible) are outputted to the display unit or the like (not shown) ofthe management server 101 and the processing routine is finished.

A mechanism for switching the path by the host computer 102 and thestorage apparatus 103 upon occurrence of the fault will now be describedwith reference to FIG. 12. (FIGS. 1 to 11 are also properly referred to)

FIG. 12 is a diagram showing an example of the path switching when thefault occurs. As shown in FIG. 12, the initiator (the host computer 102)and the target (the storage apparatus 103) use two network interfaces(network I/F 304A and 304B and network I/F 206A and 206B), respectively,and are connected to the different interfaces of the routers 104,thereby duplexing the path.

In FIG. 12, the path which is connected from the network I/F 304A of thehost computer 102 to the network I/F 206A of the storage apparatus 103through the routers 104A, 104B, and 104F is assumed to be a path 1201.The path which is connected to the network I/F 206B of the storageapparatus 103 through the network I/F 304B of the host computer 102 andthe routers 104E, 104D, and 104C is assumed to be a path 1202.

The paths 1201 and 1202 are connected to the storage apparatus 103through the different routers 104, respectively. It is assumed here thatthe path 1201 is the active path and the path 1202 is the standby path.

When the fault occurs in the router 104B here, the routers 104A and 104Fcannot execute the reroute. Therefore, the management server 101determines that it is necessary to switch from the path 1201 to the path1202 and transmits an instruction message to switch the networkinterfaces to be used to the initiator (the host computer 102) and thetarget (the storage apparatus 103). The instruction message hereincludes not only the node names and the addresses of the initiator andthe target and the LU numbers but also the session ID.

In the initiator (the host computer 102) and the target (the storageapparatus 103), the network interfaces to be used are changed inresponse to the switching instruction from the management server 101.

For example, the initiator (the host computer 102) changes the networkI/F 304A to the network I/F 304B. The target (the storage apparatus 103)changes the network I/F 206A to the network I/F 206B.

The initiator (the host computer 102) is connected to the target (thestorage apparatus 103) by the same session ID by the predeterminedcommunication control program by using the network interface designatedfrom the management server 101.

If the standby path is not registered in the same session ID withreference to the session management table or if it is determined thatthe communication is impossible (DOWN) also in the standby path due tothe same fault with reference to the status field 807 (refer to FIG. 8)in the path management table, the management server 101 does not executethe path switching process but outputs the message showing that thefault occurred in the path and the message showing that the path cannotbe switched (the automatic recovery is impossible) to the display unitor the like (not shown) of the management server 101.

Processes in the case where the path in which the fault occurred isrecovered will be further described. Upon detection of the pathrecovery, the management server 101 transmits a status confirmationrequest to the network apparatus 104 existing in the fault position atevery predetermined period and, when the response from the networkapparatus 104 is normal and the information of each interface is normal,it is determined that the fault path has been recovered, or theadministrator can also manually input information indicative of the pathrecovery to the management server 101 when the fault of the network 105is recovered.

The management server 101 again collects the path information of therecovered path through the network information collecting unit 502 andthe path management table is updated by the path information managingunit 504. Further, the active path discriminating unit 506 compares theperformance such as band and the number of hops of the recovered pathwith that of the active path. In the case where the performance of therecovered path is better than that of the active path (for example, whenthe band is larger or the number of hops is smaller), the path settinginstructing unit 507 again transmits the path switching instruction. Inthe host computer 102 and the storage apparatus 103, the instruction isreceived and the active path is switched and returned to the active pathbefore the occurrence of the fault. In the case of switching the path,the message showing that the path switching is executed is outputted tothe display unit (not shown) of the management server 101.

By the above operation, in the access from the host computer 102 to thestorage apparatus 103, the host computer 102 can use the optimum path.Even at the time of the occurrence of the path fault, the managementserver 101 grasps the situation of the network 105 and can execute theswitching process of the proper path from the host computer 102 to thestorage apparatus 103.

The management server 101 according to the embodiment can be realized bythe path managing program for executing the processes as mentioned aboveand such a program can be stored in a computer-readable storing medium(CD-ROM or the like) and provided. The program can be also providedthrough the network.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A storage network management server for instructing to switch pathswhen a fault occurs in a network which connects one or more informationprocessing apparatuses and one or more storage apparatuses, comprising:a storing apparatus for storing, every session, a session managementtable showing identification information of the information processingapparatus and the storage apparatus serving as initiators and thestorage apparatus serving as a target in said session, identificationinformation of the path which is being used at present in said session,and identification information of a standby path; an event notificationreceiving unit for receiving event notifications regarding the faults ofeach of said apparatuses and network apparatuses connected to each ofsaid apparatuses from said one or more information processingapparatuses and said one or more storage apparatuses; an active pathdiscriminating unit for making discrimination to switch said active pathto said standby path with reference to said session management table inthe case where it is determined on the basis of a transmitting source ofsaid received event notification and contents of said event notificationthat the fault has occurred in one of said network apparatuses in thepath which is being used at present by each of said apparatuses; and apath setting instructing unit for transmitting the instruction to switchfrom the active path to said standby path to each apparatus on the basisof a discrimination result of said active path discriminating unit.
 2. Aserver according to claim 1, wherein said storing apparatus furtherstores a path management table showing address information of thenetwork apparatuses through which data is passed in said path everyidentification information of said path, and said active pathdiscriminating unit is constructed so as to discriminate in such amanner that if it is determined on the basis of the transmitting sourceof said received event notification and the contents of said eventnotification that the fault has occurred in one of said networkapparatuses in the path which is being used at present by each of saidapparatuses, the network apparatuses through which the data is passed insaid path in which the fault has occurred is specified with reference tosaid path management table, information of said specified networkapparatus is collected, it is determined on the basis of the collectedinformation of each of said network apparatuses that one of said networkapparatuses is reconstructing a path, and when a notification indicativeof completion of the reconstruction of the path is not received fromsaid network apparatus under the path reconstruction for a predeterminedperiod of time after said discrimination about whether or not the pathis being reconstructed, a decision is made so as to allow each of saidapparatuses to switch from the active path to said standby path.
 3. Astorage network managing method for instructing to switch paths when afault occurs in a network which connects one or more informationprocessing apparatuses and one or more storage apparatuses, wherein astorage network management server comprising a storing apparatus forstoring, every session, a session management table showingidentification information of the information processing apparatus andthe storage apparatus serving as initiators and the storage apparatusserving as a target in said session, identification information of thepath which is being used at present in said session, and identificationinformation of a standby path, an event notification receiving unit forreceiving event notifications regarding the faults of each of saidapparatuses and network apparatuses connected to each of saidapparatuses from said one or more information processing apparatuses andsaid one or more storage apparatuses, an active path discriminating unitfor making discrimination to switch said active path to said standbypath with reference to said session management table in the case whereit is determined on the basis of a transmitting source of said receivedevent notification and contents of said event notification that thefault has occurred in one of said network apparatuses in the path whichis being used at present by each of said apparatuses, and a path settinginstructing unit for transmitting the instruction to switch from theactive path to said standby path to each apparatus on the basis of adiscrimination result of said active path discriminating unit is allowedto execute the steps of: receiving the event notifications regarding thefault of each of said apparatuses and the faults of the networkapparatuses connected to each of said apparatuses from each of saidapparatuses; on the basis of the transmitting source of said receivedevent notification and the contents of said event notification,discriminating whether the fault has occurred in each of saidapparatuses or the fault has occurred in one of said network apparatusesin the path which is being used at present by each of said apparatuses;if it is determined in said discriminating step that the fault hasoccurred in one of said network apparatuses, discriminating whether ornot the standby path exists in said session with reference to saidsession management table; and if it is determined in said discriminatingstep that said standby path exists, transmitting an instruction forallowing each of said apparatuses to switch from the active path to saidstandby path.
 4. A method according to claim 3, wherein said storingapparatus further stores a path management table showing addressinformation of the network apparatuses through which data is passed insaid path every identification information of said path, in the step ofdiscriminating whether the fault has occurred in each of saidapparatuses in the path which is being used at present by each of saidapparatuses or the fault has occurred in one of said network apparatuseson the basis of the transmitting source of said received eventnotification and the contents of said event notification, if it isdetermined that the fault has occurred in one of said networkapparatuses, a step of specifying the network apparatuses through whichdata is passed in said path in which the fault has occurred withreference to said path management table and collecting information ofeach of said network apparatuses; and a step of discriminating whetheror not one of said network apparatuses is reconstructing a path on thebasis of said collected information of each of said network apparatusesare further executed, and a step of discriminating whether or not thestandby path exists in said session with reference to said sessionmanagement table when one of said network apparatuses is reconstructingthe path in the step of discriminating whether or not one of saidnetwork apparatuses is reconstructing the path and a notificationindicative of completion of the reconstruction of the path is notreceived from said network apparatus under the path reconstructionwithin a predetermined period of time; and a step of transmitting aninstruction to switch from the active path to said standby path to eachof said apparatuses if it is determined that said standby path exists inthe step of discriminating whether or not the standby path exists insaid session are executed.
 5. A path managing program for allowing acomputer to execute a storage network managing method according to claim3.
 6. A path managing program for allowing a computer to execute astorage network managing method according to claim
 4. 7. A storagenetwork management server for managing a network which connects one ormore information processing apparatuses and one or more storageapparatuses, comprising: a storage access information collecting unitfor obtaining access information including identification informationand numbers of interfaces of the information processing apparatus andthe storage apparatus serving as initiators and the storage apparatusserving as a target in a connecting session of each of said apparatusesfrom said information processing apparatuses and said storageapparatuses; a network information collecting unit for obtaining, fromeach of network apparatuses, construction information of said networkincluding the interface numbers of said network apparatuses constructingsaid network and addresses set in said interfaces and path informationincluding identification information of the network apparatuses throughwhich data is passed between the apparatuses serving as said initiatorsand the apparatus serving as said target; a path managing unit forforming a path management table showing the identification informationof the apparatuses serving as said initiators and the apparatus servingas said target and the identification information of the networkapparatuses through which the data is passed with reference to saidaccess information, said construction information, and said pathinformation each time each of said apparatuses is connected; a storingapparatus for storing a session management table showing theidentification information of the apparatuses serving as said initiatorsand the apparatus serving as said target in said session and theidentification information of the path that is being used and said pathmanagement table; an active path discriminating unit for determining thepath which is being used in each apparatus in said session withreference to said session management table and said path managementtable; and a path setting instructing unit for notifying each of saidapparatuses of the path determined in said active path discriminatingunit.
 8. A storage network management system including one or moreinformation processing apparatuses, one or more storage apparatuses, anda storage network management server according to claim 7.